In the last decade there has been rapid progress towards the development of cell transplantation efforts for the potential treatment of retinal degenerative disorders. Retinal transplants have been attempted both in the anterior chamber and the posterior segment of the eye. RPE cells can be transplanted in the host subretinal space, and such transplants seem to protect degenerating photoreceptors in the RCS strain of rats; RPE cell transplants in patients with macular degeneration have recently been attempted. Despite the promising outlook of retinal cell transplantation, there are many features and problems that need to be resolved, including the critical issue of the availability of ex-vivo tissue and the large number of patients that could benefit from such therapy. An alternative approach involves the use of a prosthesis that responds to light by generating an electric signal, which in turn stimulates the visual system. There is sparse evidence suggesting that postreceptoral retinal cells may preserve their function after photoreceptor degeneration, so that they could be activated by transplanted photoreceptors as much as implanted microprostheses. The principal investigator and the Co-investigator have developed semiconductor-based microphotodiode array (SMA) implants, containing individual units of 20x20 um that do not require external power source, and that can be placed permanently in the subretinal space to act as a retinal prosthesis.